Oncological outcomes of preoperatively unexpected malignant tumors of the parotid gland.

PURPOSE: Unexpected parotid cancers are often encountered due to inaccuracies in the preoperative evaluation. This study aimed to examine the clinical characteristics and oncological outcomes of these cancers and to propose the appropriate management strategy.

METHODS

This is a multicenter case series study in which a total of 302 patients were diagnosed postoperatively with parotid cancers between 2003 and 2017. Of these, 85 cases without evidence of malignancy prior to surgery but identified as malignant on postoperative pathology were included.

RESULTS

Of 85 patients, 76 and 9 underwent superficial and total parotidectomy, respectively. A positive resection margin was present in 24.7% of the cases. Postoperative radiotherapy was administered to 43.6% of patients; 4.2% had a local recurrence, and no patients died of the disease. The 5-year overall and relapse-free survival rates were 100.0% and 95.2%, respectively. Patients who underwent piecemeal resection had significantly poorer oncologic outcomes. Age, sex, histologic grade, T stage, extracapsular extension, resection margin status, and postoperative radiotherapy did not affect recurrence and survival.

CONCLUSION

Preoperatively unexpected parotid cancers had excellent local control and overall survival despite positive or close resection margin, with or without postoperative radiotherapy. Therefore, patients with unexpected parotid malignancies may benefit from less aggressive postoperative management option.